A digital video signal recorded to a digital versatile disks (DVD) disk commonly uses eight-to-sixteen modulation (EFM) in converting data bytes of the digital video signal into a bitstream suitable for the DVD disk. The modulation controls a digital sum value (DSV) of the bitstream to make a modulated code either DC-free or at least small. Conventionally, two bitstreams are generated from input data in the digital video signal during the EFM process. A stream 1 has primary synchronization codes and a 16-bit codeword for each of the 91 bytes in the input data. A stream 2 includes secondary synchronization codes and a 16-bit codeword for each of the bytes in the input data. The stream having a smaller DSV value is selected as the final modulated bitstream.
Since the final selection of either the stream 1 or the stream 2 is unknown until modulation has completed, a conventional EFM modulation circuit stores both streams simultaneously. Saving the two full bitstreams in the EFM circuit utilizes 2 streams×16 bits per codeword×91 codewords per stream=2880 bits of register or memory space. Storing the 2880 bits uses a considerable amount of silicon area.